In the prior art, exercise of the leg muscles, and particularly the large leg muscles, commonly is presented in connection with a "hack squat" machine such as described in U.S. Pat. No. 4,333,644. Whereas this machine is said to effectively isolate the muscles to be exercised, it is this feature that results in limiting the exercise possible with this machine to those leg (and back) muscles that lift (or lower) the torso along a straight line path. This type of motion is unnatural and calls into play less than all the muscles sought to be exercised. Being an unnatural movement, the exercise motion further fails to provide the kind and range of motions that strengthen those muscles employed in natural squatting activities and particularly does not include those muscles that aid in rotation of the femur in the hip joint.
Other known leg exercise devices employ vertical lifting of weights using the legs as with barbells or as by lying on one's back and using the legs to perform vertical pushups of weights. These and other devices present known dangers to users such as injury to the user in the event of muscle cramps, fatigue, or slips. Likewise, they are not capable of effectively and efficiently accommodating selectable degrees of motion.